The present invention relates to a new and improved construction of marine vessel propeller equipped with a nozzle and comprising propeller vanes or blades, each of which defines a vane or blade axis about which the corresponding vane is pivotable. The vane axes intersect at an intersection point which is located on the propeller axis.
In known marine vessel propellers of this type a minimum gap formed between the outer edges of the vanes or blades and the inner surface of the nozzle only can be maintained at one single position of the vanes or blades, namely, at the region of an angle of attack having a value of zero at which no driving force exists. In the operative position and with a large angle of attack at which high efficiency has to be attained wedge-shaped expanding or widening gaps are formed between the ends of the vanes or blades and the inner surface of the nozzle which decrease the efficiency of the propeller-nozzle unit. Furthermore, there exists the danger that foreign bodies can enter the wedge-shaped gap between the end of one of the vanes or blades and the inner surface of the nozzle and which may damage the propeller vane or blade.